Improvement in watchmakers  chucks



10B nnANssml Improvement in Watchmakelfs` Chucks.

No. v120,988.v Paranzednowwnan.

Witnesses'.` lIriver-'amr'.

JoB MANsIR, or nionMoND, MAME.

IMPROVEMENT IN WATCHMAKERS CHUCKS. v

Specification forming part of Letters Patent No. 120,988, dated November 14, 1871.

To atl whom it may concern:

Beit known that I, JOB MANSIR, of Richmond, in the county of Sagadahoc and State of Maine, have invented a new and valuable Improvement in Chucks; and I do hereby declare that the following is a full, clear, and exact description of the construction and operation of the same, reference being had to the annexed drawing making a part of this specification, and to the letters and figures of reference marked thereon.

Figure 1 of the drawing is a back view of my invention. Fig. 2 is a central longitudinal section thereof.

This invention has relation to watchmakers chucks; and it consists in the construction and novel arrangement of devices wherebyT the pinion may be centered between smooth plates, the spring being placed on the rear of the chuck plate, as hereinafter described.

In the drawing, A represents the faceplate of the chuck provided with two screws a a. B represents the chuck-plate or bed-piece, having two countersunk holes b b arranged to receive the screws a a. C represents a center-block or stem, having a shoulder, o, which serves to keep the chuck at a proper distance from the lathe, to which it is designed to be secured by the stem C. An opening, z', is made from the face of the plate B into the body of the stem C, in a central line, the object of which is to receive the stem of the pinion or work to be centered. The exterior oi' the stem C is preferably cylindrical, and it serves as a guide for the elliptical or bar-spring D, which divides and passes on each side of said stem. K K represent thumb-nuts, which pass into the countersunk holes of the plate B, the same being provided with hanches, z, by which they are kept from flying out when the nuts are turned entirely off the screws a. Shoulders k. are formed on the thumb-nuts, and serve to engage with the ends of the spring D through eircular openings -.in which said thumb-nuts pass. Instead of the elliptical spring D, the thumbnuts may be furnished with separate springs. It is apparent that when the thumb-nuts are turned down upon the screws a a, the disk of the pinion will be held between the smooth plates A B by an elastic or spring-pressure due to the spring D.

I am aware that it is not new to employ a spring-pressure in watchmakers7 chucks 5 hence I do not claim such broadly, but- What I claim as my invention, and desire to secure by Letters Patent, is-

The combination, with the perforated chuck plate B, of the faceplate A, screws a a, thumbnuts K K, and back-spring D, substantially as specified.

In testimony that I claim the above I have hereunto subscribed my name in the presence of two witnesses.

Witnesses: JOB MANSIR.

A. B. GAUBERT, A. G. SPAULDING. (36) 

